Well, things look good.
I found a little box with clasps at Michael's.
I built a little container within it out of acrylic sheets and silicon glue. The lip has silicon on it so it'll make a good seal with the membrane.
The top is the lid with a home made gasket make out of silicone.
Everything assembled with silicone for extra measure.
It is leak free.
So then it got dunked into my high tech tank.
It rose at about 1ppmw per minute. Final reading was 44.01 ppmw in my tank. It took 30 minutes to get there from 6 ppmw.
All in all a successful experiment. I have ideas on making it even more responsive. Adding more holes in the lid might help and I made a thin sheet of silicone I will replace the breather bag.
So now the next step if to hook this up to a relay to control the solenoid.